Part 1) A cop car traveling at 25 m/s has a siren producing a frequency of 700 Hz. A felon jumps on his motorcycle and speed off in the opposite direction of 15 m/s. What frequency does the felon hear as he sped away (speed of sound is 343 m/s)?
Part 2) The cop does a U-turn and speeds towards the felon at 30 m/s, while the felon speeds up to 20 m/s. What frequency does the felon hear as he sped away (speed of sound is 343 m/s)?
Part 3) What if the felon then sped up to 30 m/s and all other conditions remained the same?

1) 621.8 Hz

2) 719.3 Hz

3) 700 Hz

Explanation:

1)

The Doppler effect occurs when there is a source of a wave in relative motion with respect to an observer.

When this happens, the frequency of the wave appears shifted to the observer, according to the equation:

where

f is the real frequency of the sound

f' is the apparent frequency of the sound

v is the speed of the sound wave

is the velocity of the observer, which is negative if the observer is moving away from the source, positive if the observer is moving towards the source

is the velocity of the source, which is negative if the source is moving towards the observer, positive if the source is moving away

In this problem we have:

f = 700 Hz is the frequency of the siren

v = 343 m/s is the speed of sound

is the velocity of the car with the siren

is the velocity of the felon (he's moving away from the siren)

So, the frequency heard by the felon is

2)

In this case, the cop does a U-turn and speeds towards the felon at 30 m/s.

This means that now the siren is moving towards the observer (so, becomes positive), while the sign of still remains positive.

So we have:

f = 700 Hz is the frequency of the siren

v = 343 m/s is the speed of sound

is the velocity of the car with the siren

is the velocity of the felon

So, the frequency heard by the felon is

3)

In this case, the felon speeds up to 30 m/s.

This means that now the felon and the siren are moving with the same relative velocity: so, it's like they are not moving relative to each other, so the frequency will not change.

In fact we have:

f = 700 Hz is the frequency of the siren

v = 343 m/s is the speed of sound

is the velocity of the car with the siren

is the velocity of the felon

So, the frequency heard by the felon is

So, the frequency will not change.

a) are muscles that have bands.

happy to

pls mark as brainliest

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